Rare Venus Transit of Sun Occurs in June: Skywatching Travel Tips

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Mark your calendars! On June 5-6, a rare celestial event called a
transit of Venus will take place, and it won't be repeated in
your lifetime.

During the transit,
Venus will pass directly in front of the sun from Earth's
perspective, appearing as a small, slowly moving black dot. The
last time this happened was in June 2004, but the next one won’t
take place until December 2117. This is the last chance for
anyone alive today to see the rare celestial sight.

Unlike a total eclipse of the sun, which is visible only within a
long narrow track traced by the moon’s shadow, during the
2012 transit of Venus the entire hemisphere of Earth facing
the sun will get to see at least part of the planet’s solar
crossing.

The entire transit will be widely visible from eastern Asia,
eastern Australia, New Zealand and the western Pacific, as well
as Alaska, northern Canada and almost all of Greenland. [ Venus
Transit of 2004: 51 Amazing Photos ]

For much of North and Central America and northwestern South
America, skywatchers will be able to see the start of the transit
on the afternoon of June 5. But they'll miss its end, since the
sun will have set before Venus exits the the solar disk.

For viewers in central and eastern Europe, western and central
Asia, eastern Africa, India and western Australia, the transit
will already be under way by the time the sun rises on the
morning of June 6 (local time), so they’ll be able to watch the
transit’s end from those locations.

WARNING: NEVER look at the sun directly with
your naked eye or through cameras, binocularsor small
telescopes without proper filters. Doing so can result in
permanent eye damage or blindness.

Use a No. 14 welder’s glass filter, or purchase special solar
filters from companies such as Thousand Oaks, Kendrick Astro
Instruments or Orion Telescopes & Binoculars, and fit them
securely over your equipment.

The safest and simplest technique is to observe the transit
indirectly using the solar projection method. Use your telescope
or one side of your binoculars to project a magnified image of
the sun’s disk onto a shaded white piece of cardboard. The
projected image on the cardboard will be safe to look at and
photograph.

Serious skywatchers will want to
see the entire transit from start to finish — that is, from the
moment Venus’ disk first touches the northeastern edge of the sun
to the time the planet completely leaves the west-northwest side
of the solar disk, a journey that will take six hours and 40
minutes to complete. [ Venus
Transit Video: Between Earth and a Hot Place ]

According to eclipse meteorologist Jay Anderson of the Royal
Astronomical Society of Canada in Winnipeg, Manitoba, "one
country stands out above all others for its good weather during
the event: Australia, and only eastern and central Australia at
that, as the transit starts just before sunrise in the west.
Sydney is fine, but observers in Perth will miss the entry of the
planet onto the solar disk."

Anderson said satellite studies suggest that the average
cloud cover during the transit will be lowest in Australia's
Northern Territory, which should enjoy more than 90 percent of
the maximum possible amount of sunshine at that time.

In Southeast Asia and China, the
monsoon season will be in its early stages, and cloudiness
should therefore be endemic, he added.

"Over Africa, the Middle East and India, good weather prospects
stretch from the Sahara across Egypt and Turkey into Iraq and
Afghanistan," Anderson said. "For an absolute sure-fire guarantee
of a view of at least a part of the transit, it’s hard to beat
the statistics for Riyadh in Saudi Arabia — an average cloud
amount of 3 percent."

Venus Point, Tahiti

Venus Point in Tahiti, French Polynesia, is also being touted as
a prime transit-viewing destination owing to its special
historical connection.This site on the island’s northernmost
coast was where British
captain James Cook observed the transit of Venus in June
1769.

After 243 years, the transit returns once again to Tahiti. On
June 6, the planet’s entry, or ingress, into the solar disk can
be viewed shortly after local noon. Unfortunately, its exit, or
egress, will not be visible since the sun will set about an hour
before the transit ends.

Anderson noted that French Polynesia is in its dry season in June
and the weather should be cooperative.

"Sunshine averages 67 percent of the maximum at Papeete [Tahiti’s
capital], among the better spots in the South Pacific," he said.

United States and Canada

In the United States and Canada, the entire transit can be seen
only from Hawaii and Alaska, as well as the Yukon and parts of
British Columbia, the Northwest Territories and Nunavut. For the
rest of the United States and southern Canada, the sun will set
while the transit is still in progress.

In Atlanta and Boston, for example, the transit won't even start
until 6:04 p.m. local time; in San Francisco and Seattle, Venus
begins crossing the solar disk at 3:06 p.m.

The Hawaiian Islands are a popular transit-viewing destination,
with Honolulu on Oahu experiencing 74 percent of possible
sunshine in June. From the summit of Mauna Kea on the Big Island,
where some of the
world’s largest telescopes are located, the transit’s ingress
can be seen overhead in the sky, but by the transit’s egress, the
sun will be very close to the horizon so low clouds or
atmospheric turbulence could pose a challenge for viewers.

For residents of Anchorage, Alaska, the late-afternoon sun will
appear much higher in the sky (14 degrees) at transit egress.
However, the city enjoys only 46 percent of maximum possible
sunshine during June.

Canadians will have to travel to the country’s northern regions
to see the transit in full. Yellowknife, the capital city of
Canada’s Northwest Territories located just 320 miles (515
kilometers) south of the Arctic Circle, "offers the most
promising cloud and sunshine statistics of any northern site,
Europe or North America, with sunshine hours averaging 64 percent
of the maximum,"Anderson said.

In the lower 48 American states, the Pacific coast and the
deserts of the Southwest offer excellent weather prospects in
early June for viewing the partial transit.

Anderson said cloud statistics indicate that coastal California
enjoys an average of 60 to 65 percent of the maximum possible
sunshine for June, while Tucson, Ariz., and the surrounding areas
experience 93 percent.

Elsewhere in the country, cloudiness tends to increase steadily
as you go from west to east. June is prime thunderstorm season in
parts of the United States, Anderson said, reaching a maximum
over the Appalachians and along the Atlantic seaboard.

Nevertheless, if you have a car, Internet access to check the
latest weather forecasts and satellite images, and a few days to
spare,you should be able to find a suitable spot to see this
last-in-a-lifetime transit of Venus.